Well radioactivity logging apparatus



5, 1954 s. KRASNOW ETAL 2,665,386

WELL RADIOACTIVITY LOGGING APPARATUS Original Filed 001:. l, 1941 3 Sheet s-Sheet l INVENTORS.

SHELLEY KRASNOW MEYER JOSEPH TEST mfilwu THEIR ATTORNEYS.

Jan. 5, 1954 s. KRASNOW EAL 2,665,386

WELL RADIOACTIVITY LOGGING APPARATUS Original Filed Oct. 1, 1941 3 Sheets-Sheet 2 88 82 as as I 7/a I i 7/ E: /33

INVENTORS. SHELLEY KRASNOW MEYER JOSEPH TEST THEIR ATTORNEYS.

Jan. 5, 1954 s. KRASNOW ETAL ,665,33

WELL RADIOACTIVITY LOGGING APPARATUS Original Filed Oct. 1, 1941 5 Sheets-Sheet 3 FIG .5.

INVENTORS. SHELLEY KRASNOW MEYER JOSEPH TEST THEIR ATTORNEYS.

Patented Jan. 5, 1954 WELL RADIOACTIVITY LOGGING APPARATUS Shelley Krasnow, Fairfax, Va., and Meyer Joseph Test, Kansas City, Mo., assignors to Schlumberger Well Surveying Corporation, Houston, Tex., a corporation of Delaware Original application October 1, 1941, Serial No. 413,240. Divided and this application January 30, 1951, Serial No. 208,609

6 Claims. (Cl. 250-83-6) This invention relates to apparatus. for measuring radioactivity in bore holes. This subject has been taught in considerable detail in the earlier work of one of the co-inventors. The present apparatus is intended to provide improved means for the expeditious and accurate measurement of radioactivity in deep bore holes.

This application is a division of my parent application Serial No. 413,240, filed October 1, 1941, for Borehole Radioactive Apparatus, now abandoned, of which a division having the same disclosure, Serial No. 27,857, filed May 19, 1948, for Energizing Systems for Borehole Radioactivity Apparatus is still pending.

It is an object of the invention to provide a convenient radioactive bore hole apparatus, capable of making measurements of radioactivity at a desired depth in a bore hole.

It is a further object of the invention to provide such an apparatus which will record continuously the radioactivity measured at different depths.

It is a further object of the invention to provide an apparatus which will record faithfully and will integrate pulses from a counter device operated in the bore hole.

It is a further object of the invention to obtain a heightened result in the measurement of radioactivity.

It is a further object of the invention to provide a compact counter element and associated circuit which may be contained within a narrow cartridge capable of being lowered into a bore hole.

It is a further object of the invention to provide radioactive bore hole apparatus which may be easily assembled and disassembled, and which is protected from mechanical shocks when in use.

It is a further object of the invention to provide an improved system for amplifying and transmitting pulses produced by a radioactive measuring system utilized in a bore hole.

Other objects and advantages of the invention will be apparent from the following drawings, in which:

Fig. 1 represents a schematic view of the apparatus as used in a bore hole;

Fig. 2 represents a longitudinal cross-sectional view of the cartridge shown in Fig. 1, showing the relative arrangement of the elements;

Fig. 3 shows a detail indicating the manner of mounting the circuit element in the embodiment shown in Fig. 2;

Fig. 4 shows the circuit diagram of the apparatus, indicating wiring of the parts within the cartridge;

Fig. 5 shows the wiring diagram of that portion of the apparatus at the surface of the earth; and

Fig. 6 shows a plan view of one of the sections shown in Fig. 3.

i represents a bore hole drilled in the earth in which may or may not exist a metallic casing 2. The bore hole may or may not be filled with liquid 3. Suspended within the bore hole is an element 4, serving to contain certain of the elements of the apparatus and to place these elements proximate to the strata from which it is desired to obtain indications. suspending the element 4 is a multiconductor cable 5, which serves to position the element 4, to conduct energy into the said element and also to receive responses therefrom. The cable 5 passes over a measuring wheel 5, which at all times indicates the depth of the element 4, and which may be connected to other portions of the apparatus to record the depth against any other desired quantity. The wheel 6 rests upon a support 1 at the top of the bore hole. Cable 5 may be reeled or unreeled by means of a drum 8, which has slip rings allowing connection to be made during rotation and for any position of the drum to a number of stationary wires 9. These wires lead to apparatus 10 and II, whose purpose will be hereinafter described.

Referring now particularly to Fig. 2, l2 represents the exterior of the cartridge 4. This is preferably made of a strong metal such as high strength steel, and may be provided with a corrugated exterior surface l3 where the rays are to pass through. At either end of the member i2 internally threaded portions 14 and i5 are provided into which suitable supports and closures may be fastened. At the lower end of the cartridge is a closure l6 which may be screwed into the-tube l2 and which bears aganist a gasket represented schematically as I"! to shield the apparatus against high hydrostatic pressures. Above the upper portion of the element i6 is a threaded insert l8 which serves as a mechanical support. This bears against a coil spring is, which in turn bears against an insulating block 20. Fastened rigidly to the insulating block is a radioactive sensitive element 2! which may be of the type disclosed in our copending application Serial No. 27,856, filed May 19, 1948, for

' Construction of Geiger-Muller Tube.

Insulating ring 22 is fastened rigidly to the upper end of the radioactive sensitive element 2!, and a preferably metallic tube 23 rests upon the upper end of this insulator. An additional threaded insert Me is placed above tube 23, and Serv s o compress a coil spring -I 9. This assemblage maintains the element 2| in a sort of floating support, held by springs above and below. The elements 20 and 22 will make light frictional contact against .the walls of .the tube 1.2,, which will serve to :damp mechanicalaoscillations. This may be aided by providing small springs which bear against the interior wall of the tube 12 and 18a, through pressure-tight.insulating bushings 26 and 21, respectively, and further to thesurface of the earth. These wires are attached in mechanically strong fashionto element 28 so that they may be used to support "the entire apparatus.

Lying above insulating plate 22 is assemblage 28, containing the auxiliary elements and other portions .requiredfor operation. This is .inform of a relativelyrigid frame upon I which .are mounted the vacuum tubes, condensers andre= sisters necessary for operation. The frame-28 rests upon springs 66a, which maybe three in number and. is also held downward bysprings 30, which may. alsobe three number.

The assemblage 28 is-preferabl-y made in the form of a unitary structure .which can v.be inserted into the cartridge 12-or removed con- .veniently-at'will.

The assemblage maybe made of a number of plates such as 54. (Fig. 3), whichare held in rigid spaced relation by-means of rods 58, and-separators 159. Nuts 5'8 serve to clamp theentire assemblage together. The number of'rods 56 may be two, three, four, or more in number. Each of the elements 54 may be in the form of a disk of metal provided, for example, with vacuum tube sockets such as B (Fig. v6) and openings such'as 6 I, through which wiredconnections may be taken from one level into another. Circuit elements such as condensers represented schematically as--l, may be fastened to a plate such as .53." The entire assemblage is wired-together so thatpnly the input and output. wires extend belowand:above,'respectively.

A detailed the spring mounting of the assemblage28 is shown in .Fig. 3. Here threaded-rods 56 :pass through a disk '64, which is attached rigidly to the top of counter tube 21 by means of screws 165. At the lower end of the rod :56, a shoulder portion :68 is provided. -Underneath-this aresprings 66a, whichma y be of coil form. Underneath disk 54 an-additiona'l set of springs is provided. Nuts; are fastened at the lower portion of rod 56, thus providing a fioatingspring mounting for the entire assemblage 28.

' It will be noted that the spring mountings for the counter tube 2| and the assemblage"28 are individual. The tube structures should preferably have different periods of oscillation so as to tend to suppress oscillations; It isunderstood that the unitary assemblage '28. may holdt-he elements of "any desired circuit .or auxiliary .apparatus .to operate the radioactive sensitive element, and to receive responses therefrom.

Referring. now particularly to Fig. 4,.69 and '10 represent the input ,power lead of the apparatus, 69. being a grounded negative lead, and 70 being .a positive lead. The voltage between these 'two may be 220 or 250 volts or any desired value. This voltage is applied to the filaments of the various vacuum tubes 13 and 14, through resistors?! and Ha; This reduces the voltage to the proper value for all the filaments appearing. The voltage across resistor Ha is also applied to the plate of the vacuum tube 14 as shown.

Voltage .Jfor" the Geiger-.Miillerltubelzji is provided solely by a charged condenser 82 which is .made of suificiently large capacity and is sufliciently well insulated for this purpose. The cont-denser 8.2 is adapted to be charged electrically .a'tthe surface of the earth, placed in the apparatus, and lowered therewith without any other usource'of voltage for the Geiger-Muller tube 2!.

' With a .-condenser 32 having exceptionally good insulation in itsconstruction, and a high enough capacity of say 0.1 microfarad, for example, and with the leads between the condenser 82 and the tube '2! 'sufdciently well insulated so as to obviate leakage, the'tu'be 2! (which draws an exceedingly small current of the order of 1 6 of a microampere) may be operated for several hours on one charge ofthe condenserBZ.

Where high temperatures are to 'beencountered within .the bore hole, it is desirable to mount .the condenserBZin athermal insulating enclosure of the type .shown in my vcopending application Serial. No. 203,814, filed January .2, .1951, for Temperature Compensated Bore Hole Radioactivity Apparatus.

The pulses produced by the breakdown or discharge of the Geiger-Muller tube- Z-I are-quenched by resistor 83. Such pulses are fed to condenser 84 and across resistor '85 placed between the filament and the grid of amplifier 74. Tube 14 and resistance-capacity coupled amplifier 13 both serve several functions. Tube 14 serves to amplify the pulses produced by the Geiger- Miiller tube 2!, and to invert this pulsep The original pulse is a negative-one and is inverted to form a positive pulse. Tube 73 is operatedas a class .C amplifier so that the system will be unresponsive to microp'honics. It also serves to sharpen the Geiger-Muller tube pulses. As shown, thesystem will respond only to appreciable-pulses of thesize produced by the Geiger- Miiller tube. The final amplified pulse is then led through wire 89 to the surface-of theground.

Figure 5 shows the portions of theapparatus which are preferably kept above ground.' Here the terminals which are connected below ground are-numbered in the same fashion. 'It will be seen that the input-of this apparatus, which is the output of'the apparatus below ground is represented by 89. The amplified pulse is, therefore, applied across resistor 94 between terminalsw and 8-9. Amplification is performed by resistance capacity coupled amplifiertube 9 5. and .one section of .tube flfi. Amplification by tube 95 may be omitted, particularly'if cable:noises or other disturbances-are troublesome. The resistor 91 and condenser ,asfi act as a plate supply filter for the amplifiertube 95 and prevent self-oscillation through plate coupling; Due to overloading of the tube 86; or the operation of the said tube'at a suitable position of: its characteristic, all pulses resulting from tube 95 will be of equal magnitude nomatter what the size of the pulses originally fed to the apparatus. This is desirable since the number of pulses is the criterion of importance in a counter of this type, rather than the size of the pulses orthe integrated average of the size of the pulses.

Where the output of the radioactive sensitive member is proportional to radioactivity, the tube 96 will :be operated .at'that portion of its characteristic which will'give a value proportional to 5 the input. Thus, if a proportional counter is used, or one in which the size of the pulse is dependent on the radioactive intensity, the tube 96 can be operated at the approximately linear part of its characteristic so as to give an output proportional to the size of the input pulse.

The leveled pulses resulting from amplification by tube 90 are applied through condenser I00, across the right-hand section of the same tube, operating as a diode rectifier. This rectifier charges condenser I00, which further charges condenser IOI, through resistor I25. The voltage across condenser MI is, therefore, proportional to the frequency of the pulses originally produced by the Geiger-Muller tube. This voltage is applied across a step ladder attenuator I02, with a switch I03, to select a suitable tap thereof. The voltage output of the attenuator is applied across tube I04, which has a milliammeter in its plate circuit. The plate current will be proportional to the grid voltage, and, therefore, will also be proportional to the number of pulses. The meter I05 will, therefore, read the integrated average of the pulses produced by the Geiger-Muller counter.

In series with meter I05 is an adjustable resistance I06, which is connected in series with an external meter I01. The external meter I! may be a recording type while the meter I is an ordinary indicator type. The instrument will, therefore, indicate and record simultaneously. The two meters may be placed at different localities. Alternatively, meter I01 may be replaced by any current sensitive or current responsive device. The attenuator I02 acts as a range device. -Since any proportion of the voltage appearing between the output terminals of the at tenuator may be applied across the vacuum tube I04, the range of the apparatus may be changed as desired.

The input high direct current voltage is applied to terminals H2 and H3 and is controlled by the switch H5. A resistor I32 enables voltage from H2 and H3 to be stabilized by tubes 90 and 9! for application across terminals 69 and 10. The voltage regulators 82 and 83 which are gas discharge tubes connected in series, serve to supply accurate grid and plate voltages for the variout tubes so as to assure accurate and stable operation thereof. The gas discharg voltage regulator tubes 90 and 9| serve to supply a constant direct current voltage to be fed through terminals 69 and to the apparatus below ground. Alternatively, the voltage regulator tubes 90 and SI may be mounted in the cartridge 4. 'In order to set the meters I05 and I0! to zero, a bucking circuit comprised by resistors I08 and I09 is provided. Adjustable resistor I08 is used as the zero setting resistor.

The filament voltage for the tubes which are operated at the surface of the ground is supplied preferably by a six volt or other suitable voltage supply operated by switch II 4, and furnished through supply terminals H0 and III.

Because of the high temperatures often met with in deep bore holes, it will be found necessary when transformers or other similar electrical elements are utilized, to have those units provided with an insulating varnish capable of withstanding the temperatures encountered. The same remark applies to the resistors and condensers, although where these elements are maintained in a constant-temperature enclosure as pointed out herein, such elaborate precautions are often unnecessary.

Various elements in the different circuits have been shown without a description being given of their exact function. The f ments may be told from in the respective circui art.

A representative set of values which has been found to give good results is as follows:

82-0.1 mfd. I 26-.0001 mfd. 831O ohm I21-5 meg. 84-.000075 mfd. 86-1 meg. lIa4000 ohms 81-.000075 mfd. -40 ohms I I 9-20 mfd. 881 meg. I23-% meg. 53-1 LB 4 I24 A meg.

I 33-.01 mfd. I22-1,000 ohms l Il,250 ohms 9410,000 ohms unction of these eletheir relative positions ts by those versed in the While the specific embodiment has been drawn chiefly to a Geiger-Muller system, it will be understood that most of the members can be applied to other systems such as those utilizing ionization chambers. Thus, the construction of the tube and the mode of its use may be applied to an ionization chamber apparatus. Further, the high voltage may be applied in the same way. The transmitting circuits and the association of the circuit elements may also be utilized in ionization chamber assemblages.

The scope of the invention is indicated appended claims.

a We claim:

1. In radioactivity responsive apparatus for use in a bore hole, the combination of an enclosed cartridge adapted to be lowered into the bore hole, a low current consumption radioactivity responsive device in said cartridge comprising an envelope having anode means therein and cathode means, and a source of electrical energy consisting of an isolated, relatively high capacitance, low leakage loss condenser in the cartridge connected to the anode means and the cathode means of said device and adapted to be charged electrically for this purpose, and output means in said cartridge for furnishing signals indicative of the radioactivity detected by said device.

2. A radioactivity surveying instrument for lowering into a bore hole by a cable comprising a housing containing a low current consumption device adapted to produce electrical pulses in response to radioactivity in the bore hole, a capacitance adapted to be charged at the surface of the earth to provide the entire electrical energy for said electrical pulses, and means to apply said pulses to a conductor in the cable attached to said housing.

3. In radioactivity responsive apparatus for use in a bore hole, the combination of an enclosed cartridge adapted to be lowered into a bore hole, a low current consumption radioactivity responby the sive devicci'in saidicartridge, a: source'of electrical energy for-said device consisting of are isolated capacitance mounted in the. cartridge and adapted to be charged electrically for this purpose, electron tube means in the cartridge for amplifying the output of said device, a source of electrical energy: and electrical indicating; means at the surface.- or the. earth, and electrical transmission means 7 for supplying electrical energy from said source at the surface to said, electron tube means, and for transmitting amplified signals from said electron tube means to the. indicating means, at .the surface.

4. In radioactivity responsive apparatus for use in a bore hole, the combination of an. enclosed cartridge. adapted to be lowered into a. bore hole, a radioactivity responsive device in said cartridge, a source of electrical energy for said device consisting of. an isolated capacitance mounted in the. cartridge and adapted to be charged electrically for this purpose, electron tube means. in the cartridge for amplifying the output of said device, a source ofelectrical energy at the surface of the earth, electrical transmission means for supplying electrical energy from said source at the surface to said electron tube meanajelectronic amplifier means. at the surface, electrical transmission means for transmitting output signals from said electronvtube means in the cartridge to said amplifier means, at the surface, means for rectifying and filtering the output of said amplifier means, and means for providing indications of the output of said rectifying and filtering means.

5. In radioactivity responsive apparatus for use in a bore hole, the combination of. an enclosed cartridge adapted to. be. lowered into a bore hole, a radioactivity responsive device in said cartridge, asource of electrical energy for-said device com sistingof an isolated. capacitance-mounted in the cartridge and adapted to be charged for-thispurpose, firstv electron tube amplifier means: in the cartridge for amplying the output of said device, second amplifier means-.inthe cartridge for amplifying the'output of said first amplifier means, a source of electrical energy atzthe surface of the earth, electrical transmission meansfor supplying electrical energy from said source to. said first and second amplifier means in the cartridge to. energize, the; same, electrical indicating means at the. surface, and electrical transmission means for transmitting the output: of said second. ampl-ifiiermeans; the cartridge to said indicating means at theasurface.

6; In radioactivity responsive. apparatus for use: in; a. bore hole, the combination of an enclosed cartridge adapted to. be lowered into a bore hole-,- a radioactivity responsive device in said cartridge comprising an envelope having anode means therein and cathode means, a. source or electrical energy for said device consisting of an isolated,.relatively high capacitance, low leakageloss condenser in the cartridge connected to the. anodemeans and .to the cathode means: of said device and adapted to. be. charged electrical-lyfor this purpose, first electron amplifier means inthe. cartridge for amplifying the out.- pntz of said device, second class: 0' electron amplifier means in the cartridge for amplify-ingthe output: of said first. electron amplifier means, a

source of electrical energy atthe surface of the earth, electrical transmission means for supplying electrical energy from said sourceat. the

surface. to. said first and second amplifier means in the cartridge to energize the same, electronic. amplifier means at. the; surface, electrical transmission means. for transmitting the. signal output of said second amplifier means. in the cartridge to said amplifier means. at; the surface, means for rectifying and filtering the output of said amplifier means at the surface, and means for providing indications of the output of said rectifying and filtering means.

SHELLEY KRASNOW.

MEYER: JOSEPH TEST;

References Gited the; file: oi this patent UNITED STATES PATENTS Number Name Date Re, 23,226 Bender May 9,, 195.0, 685 ,95,8. Tesla Nov. 5, 19.01 1,841,983 Ruhl'emann Jan. 19., 1932v 2,086,913 Kelly, Jr. July. 13, 1.937 2167.530. Bazzoni. et. a1. Aug, 1,. .1939 2.1.9..7A53 Hassler -n ..Apr. 16,. 19.40. 

